Katherine Jenkins says she acted "on instinct" when she intervened in a street robbery.
The opera star (39) was also attacked after going to help "an older lady being viciously mugged", her agent said.
"She was clearly in distress, screaming for help," Jenkins said.
"So many people just walked past. It was an instinct to rush over, and in doing so I got attacked as well.
"I didn't consider that people might know who I am - I gave the police my married name."
Jenkins was on her way to sing at a charity concert on the day of the incident in December.
"I was shaken up initially, but my instinct is always to keep going, so I got out there," she said.
The mezzo-soprano and mother-of-two also spoke about her marriage to US film director Andrew Levitas.
"We're constantly on the move," she said. "My husband moved to Serbia for six months to make a movie, and at that time I had a five-month-old and my daughter and an album.
"He touched down in Heathrow as I jumped in a taxi to go to Tokyo. We didn't see each other."